A semiconductor integrated-circuit card (hereinafter referred to simply as IC card) is a data carrier device in the form of a card having a microprocessor unit and an on-chip or off-chip integrated-circuit data storage memory provided on a printed circuit board on a sheet substrate.
With a view to expanding the range of applications of IC cards, there is a demand for a portable IC card data processing system. Attempts are thus made to realize a miniaturized IC card data processing system having a built-in power supply implemented by a battery. One of the most important requirements of an IC card card data processing system of this type is to minimize the consumption of the power supplied from the system to the IC card so as to extend the service life of the battery incorporated in the system. A prolonged service life would be achievable by a battery of an increased capacity. This kind of approach to increasing the service life of a built-in power supply source is however not unconditionally acceptable because of the exacting space and weight requirements of a miniaturized IC card data processing system. The power consumption of an IC card could be significantly reduced if the microprocessor unit and data storage memory incorporated in an IC card are formed by CMOS (complementary metal-oxide-semiconductor) devices featuring low power dissipation. Tremendous amounts of time and cost will however be required for the development of a new integrated circuit of such CMOS configuration.